Iodination Using Solid Catalysts

They used different catalysts for the synthesis of the desired product such as p-toluenesulfonic acid (/>-TSA), CF3SO3H, and solid-supported catalyst such as NaHS03-Si02, but these were found to be less effective. The desired product was isolated only in 25-30% yield and the use of iodine increased the product yield significantly. The reaction was carried out using 0.1 mmol of iodine. The yield of the product was decreased when 0.05 mmol of iodine was used or suppressed when the reaction was performed at room temperature. The effect of solvents, e.g., DMF or tetrahydrofuran (THF) was also examined and found to be counterproductive. 

The kinetics of the acid-catalyzed esterification reaction of 2,4,6-trimethylbenzoic acid in i-PrOH under microwave irradiation have been investigated [84], A simple and practical technique for MW-assisted synthesis of esters has been reported wherein the reactions are conducted either on solid mineral supports or by using a phase transfer catalyst (PTC) in the absence of organic solvents [85], The esterification of enols with acetic anhydride and iodine has also been recorded [86],... 

Iodine monochloride [7790-99-0], IQ, mol wt 162.38, 78.16% I, is a black crystalline solid or a reddish brown liquid. Solid IQ exists in two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats AND fatty oils). IQ is prepared by direct reaction of iodine and liquid chlorine. Aqueous solutions are obtained by treating a suspension of iodine in moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

A tandem RCM-cleavable linker for application to the solid-phase synthesis of oligosaccharides has recently been reported [136]. The system makes use of a tri-ene linker system, resulting in the fact that the RCM regenerates the active Ru catalyst without the need for an alkene co-factor. The application of this hnker was demonstrated in the hberation of a cyclopent-2-enyl mannoside from the solid support. Subsequent isomerization to the vinyl ether glycoside led to the depro-tected mannose after iodine treatment. The basic principle of the approach is out-hned in Scheme 52. 

Copper (I) iodide Copper iodide (Cul) Copper monoiodide Copper(1 ) iodide Copper(l) iodide Cuprous iodide EINECS 231-674-6 EPA Pesticide Chemical Code 108301 HSDB 271 Hydro-Giene Natural marshite. Used as a feed additive, in table salt as source of dietary iodine, catalyst, in cloud seeding. Solid mpa 588-606° bp= 1290° d = 5.63 insoluble in all solvents. Atomergic Chemetals Blythe, Williams Ltd. Cerac Greet R.W. Co. Mitsui Toatsu Nihon Kagaku Sangyo Sigma-Aldrich Fine Chem. 

The reaction requires the use of a catalyst for the alkaline earth metals, rare earth metals and aluminium. The most common approaches are the use of (in the laboratory practice only) the salts of mercury(II) such as HgC or Hg(OAc)2. Very small portions of these salts cause amalgamation of the metal surface (and thus clean it from the oxide layer) and facilitate the reaction with alcohols. The larger scale synthesis (and thus the industrial one—in the scope of pollution danger) uses the initial addition of solid iodine (1 g or less per 1(X) g ofalkoxide to be prepared). Formation of metal iodide serves both for cleaning the surface and increases also slightly the acidity of alcohols via formation of solvate complexes. In the case of barium, the application of dry ammonia gas has been reported for this purpose (Caulton, 1990 Drake, 1992). The major factor facilitating the reaction ofmetals with alcohols is the solubility of the alkoxides formed. Insoluble alkoxides form a protective layer on the surface of the metal and it hinders the reaction. Even the reaction of sodium with BuOH in toluene may be almost stopped by the formation of poorly soluble NaO Bu. 

The oxidation of alcohols to aldehydes and ketones is one of the most widely practiced of synthetic transformations. Ge Wang of the University of Science and Technology in Beijing has developed Chem. Lett. 2007, 36, 1236) a Mo catalyst that used aqueous to effect this transformation. Secondary alcohols are oxidized more rapidly than primary alcohols. Vinod K. Singh of the Indian Institute of Technology, Kanpur, has found Synth. Comm. 2007, 37, 4099) that the solid, inexpensive 6 can take the place of oxalyl chloride in the Swem oxidation. Viktor V. Zhdankin of the University of Miimesota, Duluth has devised J. Org. Chem. 2007, 72, 8149) a polymer-bound hypervalent iodine reagent that is easily separated after use, and reoxidized for reuse. 

Y. Kim, Y.-E. Sung, J.-B. Xia, M. Lira-Cantu, N. Masaki, and S. Yanida. 2008. Solid-state dye-sensitized Xi02 solar cells using poly(3,4-ethylenedioxythio-phene) as substitute of iodine/iodide electrolytes and noble metal catalysts on... 

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